(CNN) -- Mia Farrow ended her liquid-only fast aimed at calling attention to the crisis in Darfur after 12 days as her health took "a downturn," according to her publicist.

Mia Farrow's publicist says her "health has taken a downturn."

Farrow began her fast last month to call attention to the demand that "world leaders take immediate action and demand that international aid is restored" to Darfur, her publicist said.

The actress planned to fast for three weeks, but under doctor's orders she will hand off to billionaire entrepreneur Richard Branson, who will start his planned three-day fast a week early, said Jonathan Freedman.

"Over the last 12 days she has been fasting on only liquids in order to raise awareness for the horrible crisis unfolding in Darfur with the removal of 13 international aid agencies," Freedman said. "Mia's health has taken a downturn over the last couple days and her doctor has asked her to stop immediately."